Telephone system.



BATENTED MAY 19. 1-903.

I E. UMDENSTOCK. I TELEPHONE SYSTEM.

APPLICATION FILED APR. 21, 1902.

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UNITED STATES Patented May 19, 1903.

PATENT OFFICE.

TELEPHONE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 728,785, dated May 191903.

Application filed April 21 T0 at whom it may concern.-

Be it known that I, ERNEST UMDENSTOCK, a citizen of the United States,residing at Reading, in the county of Lyon and State of Kansas, haveinvented certain new and useful Improvements in Telephone Systems; and Ido declare the following to be a full, clear, and exact description ofthe invention, such as will enable others skilled in the art to which itappertains to make and use the same.

This invention relates to improvements in telephone systems, andparticularly to systems of the party-line type, wherein a number oftelephones are in series arranged along a common line.

The object of the invention is to provide simple and effective meanswhereby any two telephones in the system may be placed in connection tothe exclusion of the others, thereby enabling conversations between anytwo of the subscribers to be held secret.

With the above and other objects in view, which will readily appear asthe nature of the invention is better understood, said inventionconsists in certain novel features of construction and combination andarrangement of parts, which will be hereinafter fully described, definedin the appended claims, and illustrated in the accompanying drawings, inwhich- Figure l is a front view of a telephone-box embodying theinvention. Fig. 2 is a vertical transverse section of the same. Fig. 3is a diagrammatic view showing the circuit connections, thereversing-lever being in neutral position. Fig. 4: is a diagram showingthe manner of connecting up the telephones along the line.

Referring now more particularly to the drawings, a, a a and a representline-wire sections from which extend legs, branches, or bridge-wires Eand W, connecting the several telephone-stations 18 19 20in series,asshown in Fig. 4. The said legs E and W may be termed east and westline connections with regard to any certain station, as they connect thestation with line-wire sections leading therefrom in oppositedirections. At each telephone-station R is the receiver, T thetransmitter, I the induction-coil, B the bell, G the generator, and Bthe local bat- 1902. SerialNo.103,930. (No'model-J tery, all of whichmay be of the ordinary type now in use.

S is the telephone switch -or hook, mounted upon the pivot p and havingalong arm .9, hooked to hold the receiver and a short arm 8. Thereceiver when applied to the hook tilts the long arm of. the switchdownward in the usual way against the pressure of a spring S, whichforces said switch upward when the receiver is removed. As shown, theswitch and the signaling and reversing mechanism are contained in a boxor casing O and the induction-coil and transmitter in a box or casingO;'but they may be inclosed in a single casing or in any other preferredway.

The legs E and W are connected to two flexible spring-strips e and w,the lower free ends of which are normally adapted to come between twocontact-barsfandf. The bar fis connected with one of the binding-postson the receiver by a conductor 1, the other binding-post on the receiverbeing'connected to the secondary coil of the induction-coil I by aconductor 2. From the bar-f leads a -conductor 3, which connectsthe'same with the bell and generator B and G, which are in turnconnected with the ground through the medium of a conductor 4. Thetelephone-switch S carries an insulated bridgepiece 8 which holds thetwo strips e and w pressed into contact with the bar f, when said leveris held down by the receiver R, making a bridging-circuit through thebell and generator to the earth; but when said receiver is removed andthe long arm of the switch is tilted up bythe spring S the bridgepieceis swung out of contact with said strips, leaving the latter free tomove between the bars f f. When thus tilted upward, the short arm .9 ofthe switch-lever comes into contact/with and depresses a spring-plateswitch 25', which engages a contact i*, which is connected to theprimary coil of the induction-coil I by means of a conductor 7. Theswitch 25 is connected with one pole of the local battery B by way of aconductor 8, and the other pole of said battery is in electricalconnection with one of the binding-posts of the transmitter T throughthe conductor 9, while a conductor 10leads from the opposite post of thetransmitter to the primary coil of the induction-coil I, whereby theparts of the talking-circuit are adapted to be connected up for use whenthe receiver is detached from the telephonehook. A ground-tap 5 connectsthe secondary coil of the induction-coil with the earth.

To control the action of the contact-strips e and w, a reversingelever Lis employed, which is pivoted at l at a point between and in rear of thestrips and terminates at one end in a handle Z, which projects through aslot Z in the front of the box C to the exterior. This lever carriesblocks a it of nonconducting material to engage said strips e and w,

When the lever L is in its normal or neutral position, as shown in Fig.3, both strips e w are out of engagement with the contactbars ff. 7

The lever L cannot be used to press either strip 6 or 20 into contactwith the barf until the receiver has been removed from the switch-hook,because the bridge-piece 5 until withdrawn from engagement with saidstrips by the upward swing of the arm 3 prevents movement of the stripstoward said bar. Assuming, however, that the receiver has been removedand the switch-lever tilted by the spring S, it will be seen that whenthe lever L is in its normal or neutral position both contacts 6 and towill be out of engagement with the bars ff, so that in neither positionof the switch-hook S can the instrument be used for directly receivingand transmitting messages, although when the switch is held down by thereceiver the instrument is in circuit with the line through said stripse and w, the bar f, and the associated partsof the signal-circuit, sothat a current may be transmitted to sound the bells B or a conversationcarried on between any other two phones along the line, using theparticular instrument under discussion as an intermediate station. WVhenthe lever L is moved in one direction, however, one of the stripssay thestrip e,will be moved to engage the contactf, while the strip to willremain out of engagement with either contactforf, so that thetalking-circuit will be closed through the receiver, secondary coil ofthe inductioncoil, transmitter, local battery, and groundtap 5, thusconnecting the telephone with the east wire E and cutting out the westwire W. On the other hand, when the lever L is moved in the reversedirection from its neutral position the strip to will be forced intocontact with the bar f and the strip e allowed to move out of contactwith said bar, thereby connecting the west wire W with the parts of thetalking-circuit and closing said circuit, while at the same time cuttingout the east wire E. The restoration of the lever L to its normalposition causes both strips to assume their normal positions between thecontacts ff and throws the talking-circuit out of connection with bothline-wires. Thus it will be seen that by the adjustment of the lever Lthe telephone may be connected up to carry on a conversation over oneline-wire in one direction while cutting out the other line-wire leadingin the reverse direction, thus enabling any two subscribers in thesystem to hold communication without the conversation being overheard byany of the others. Should any attempt be made by a party at a stationintermediate to the two talking-stations to overhear the conversation,

such attempt would be defeated, for the rea son that the removal of thereceiver at the intermediate station would cause the cutting out ofcircuit of one of the line-wires, thus interrupting the conversation andnotifying the communicating parties of the interposition in circuit ofthe line of the said intermediate station.

When the parts are in the normal position, (shown in Fig. 3,) thesignal-circuit is closed and in electrical connection with bothlinewires, as will be readily seen. The movement of the leverLin onedirection when the receiver is removed causes one of the linewires to becut out and the other line-wire to be connected with the closedtalking-circuit, while the reverse action is effected upon the movementof the lever in the opposite direction. Hence it will be seen that anyone subscriber along the line may converse with another subscriber oneither side of him without liability of the conversation being everheardby a third party.

The foregoing description of the operation will be better understood byreference to Fig. 4, which shows three stations 18, 19, and 20,connected by the legs E and W with the linewire sections a, a a and aNow assuming that stations 18 and 20 are conversing, it will be readilyunderstood that the contact to at station 18 will connect line-Wiresection a with the bar f, that the contact 6 at station 20 will connectsaid station with its .barf and the line-wire section a while the twoline-wire sections 0, and a will be connected by the engagement at theintermediate station of the strips 6 and to with the bar f. The movementof the switch-levers S upon the removal of the receivers at the twostations 18 and 20 closes the local talkingcircuits and permits strip toat station 18 and strip 6 at station 20 to be moved in engagement withthe bars f at said stations and causes stripeat station 18 and strip toat station 20 to move out of engagement with the bars f at thetwo-stations, thus cutting out of connection with said stations all thestations east of station 18 and west of station 20, so that none ofthese stations can under any circumstances overhear the conversationgoing on between stations 18 and 20.

The course of the vocal currents may be traced as follows: Referringmore particularly to station 18,when the switch If t is closed and thestrip to engaged with bar fcurrent from the local battery B flowsthrough conductor 8 to and through switch t F, thence through conductor7 to and through primary of induction-coil I, thence to transmitter Tthrough conductor .10, and back to the battery through conductor 9. Thepassage of the current through the primary of coil I causes theproduction of a current by induction in the secondary of coilI, and thiscurrent passes through the conductor 2 to transmitter T, conductor 1,bar f, strip w, west wire W, to line-wire a thence through station 19,by way of conductors E, e,f, w, and W, to line-wire a thence to strip 6at station 20, to bar f, conductor 1, receiver R, conductor 2, secondaryof coil I at said station 20, and thence to ground at 5. The circuitfrom station 20 to station 18 is as follows: from battery B at station20 through conductor 8, switch 6 t and conductor 7 to primary of coil I,thence to transmitter T through conductor.

10 and back to battery through conductor 9, the current induced in thesecondary of the coil I passing through conductor 2 to receiver R,thence to bar f through conductor 1, through strip 8 and leg E toline-wire a and back along same and through station 19 in a reversemanner to that previously described along line-wire a? to leg W, strip10, and bar f of station 18, and finally through conductor 1 to receiverR, to secondary of coil I, through conductor 2, and thence to ground at5. In thus passing through the receivers and transmitters at the twostations the current pulsations aifect the diaphragms of theseinstruments and transmit sound in the well known way. It will beunderstood that as the ringer-coils at each station are wound to 'ahigher resistance than the receiver-coils the electric inertia of theringer-coils at station 19 will prevent the talking-currents from goingto ground at i and will cause them to pass from one section to the otherof the line through the barf and strips 6 and to. Now as station 19 onlyis in circuit of the line with stations 18 and 20 it will be apparentthat should the subscriber at 19 remove his receiver both strips e andu; will spring out of engagement with the barf, thus interrupting theconversation between stations 18 and 20 and notifying the conversingparties of the action of the party at the intermediate sta tion 19. If,then, the subscriber at station 19 should connect his phone with eitherstation 18 or 20 and commence conversation with one of the interruptedparties, he would be notified of the state of affairs and restore theparts at his station to their normal positions, thus connecting upstations 18 and 20 again. The same operation would ensue if stations 18and 20 were divided bya pluralityof stations, as the attempt of asubscriber at either of the intermediate stations to place thetalking-circuit of his phone into circuit of the line would cut offcommunication between the talking-stations.

In signaling any certain station from any other certain station thegenerator at the calling station is operated to send a determined numberof current pulsations along the line, as each telephone bears adistinctive number, thus giving notice to the party at the calledstation that some other station along the line desires to holdcommunication with him. The subscriber at the called station thenremoves his receiver and operates the lever L to connect his phone toone part of the linesay east-and on failing to communicate with thecalling party is made aware of the fact that the calling station lies inthe opposite direction, or west, and reverses the switch L accordinglyto connect with the west instead of the east bridge-wire. The currentimpulse furnished by the generator is broken up and transmitted to allthe phones along the line, and that portion of the current furnishedeach phone passes from the strip 6 or strip 10, as the case may be, tothe bar f, thence through the conductor 3 and sounds the bells B, andfinally passes to the earth through the ground-tap 4.

It will be seen that the bars or contacts f form part of the maincircuit, which includes the receivers at the two connected stations, thesecondary of the induction-coils, and one or the other of the strips 6and to; that the bar f forms a part of the signal-circuit, whichincludes the bells B, generator G, and ground-tap 4; that the strips 6and w are adapted to open and close either of said circuits, and thatthe switch S alternately opens and closes the local talking-circuit,consisting of the battery B, transmitter T, primary of coil I, switch tt, and the interconnecting conductors, while the switch S may beoperated to adjust the strips 6 and to, connect the telephone witheither section of a divided line extending in opposite directions fromthe telephone.

From the foregoing description, taken in connection with theaccompanying drawings, it is thought that the construction, mode ofoperation, and advantages of my improved telephone system will bereadily apparent without requiring a more extended explanation.

Various changes in the form, proportion, and the minor details ofconstruction may be resorted to without departing from the principle orsacrificing any of the advantages of this invention.

Having thus described my invention, What I claim as new, and desire tosecure by Letters Patent, is-- I 1. In a telephone system, thecombination with line-wires; of a telephone having a signal-circuitprovided with a contact, a local talking-circuit containing atransmitter and provided with a closing-switch, main talkingcircuitconnections including a receiver and .a contact, the latter beinglocated in j uxtaposition to said signal circuit contact, a switch-hookfor operating said switch to close the local talking-circuit when thereceiver is removed, contacts connected to the line-wires and arrangedbetween said main talking and signal circuit contacts, said line-wirecontacts being held in engagement with said signalcircuit contact by theswitch-hook when the receiver is on, and a reversing device for movingeither line-wire contact into engagement with the main talking-circuitcontact when the receiver is removed, substantially as described.

2. In a telephone system, the combination with line-wires; of atelephone having a signal-circuit provided with a contact, a localtalking-circuit containing a transmitter and provided with aclosing-switch, main talkingcircuit connections including a receiver anda contact, the latter being located in juxtaposition to said signal-circuit contact, a switch-hook for operating said switch to close Intestimony whereof I have hereunto setmy hand in presence of twosubscribing witnesses. ERNEST UMDENSTOOK. Vitnesses:

EVA UMDENSTOCK, HENOITT UMDENSTOCK.

